1. Field of the Invention
This invention relates to laser material processing and methods therefore and, more particularly, to a laser material processor that may be constructed by modifying an X-Y plotter and method therefore.
2. Description of the Prior Art
In a typical computer controlled X-Y plotter, a pen is positioned on a plotting board by a pair of motors. More particularly, two orthogonal components of motion of the pen are controlled by an X motor and a Y motor, respectively.
Although each of the motors may be driven at a constant speed, it should be understood that the velocity of the pen is related to the square root of the sum of the squares of the speeds of the motors. Therefore, any change in the speed of a motor almost always changes the velocity of the pen. Additionally, the speed of a motor cannot be changed instantaneously; the change occurs during a time interval associated with a motor time constant.
A deviation in the velocity of the pen from a desired velocity may be of little importance when the plotter is used to plot a curve, for example. However, when a laser engraver, for example, is constructed by replacing the pen with an apparatus for focusing coherent light upon a workpiece, the deviation of the velocity results in a corresponding change in depth of engraving into the workpiece.
It should be appreciated that by-products of laser material processing are gaseous contaminants associated with the workpiece. The plotter has not heretofore been provided with a contaminent free optical path for the coherent light to prevent damage to optical elements included in the apparatus.
There is a need for a reliable and inexpensive laser material processor that can be made by modifying a computer controlled plotter.